/*
 * Copyright (c) 2001-2004 Caucho Technology, Inc.  All rights reserved.
 *
 * The Apache Software License, Version 1.1
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 *
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in
 *    the documentation and/or other materials provided with the
 *    distribution.
 *
 * 3. The end-user documentation included with the redistribution, if
 *    any, must include the following acknowlegement:
 *       "This product includes software developed by the
 *        Caucho Technology (http://www.caucho.com/)."
 *    Alternately, this acknowlegement may appear in the software itself,
 *    if and wherever such third-party acknowlegements normally appear.
 *
 * 4. The names "Hessian", "Resin", and "Caucho" must not be used to
 *    endorse or promote products derived from this software without prior
 *    written permission. For written permission, please contact
 *    info@caucho.com.
 *
 * 5. Products derived from this software may not be called "Resin"
 *    nor may "Resin" appear in their names without prior written
 *    permission of Caucho Technology.
 *
 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED.  IN NO EVENT SHALL CAUCHO TECHNOLOGY OR ITS CONTRIBUTORS
 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY,
 * OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT
 * OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR
 * BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
 * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE
 * OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN
 * IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 *
 * @author Scott Ferguson
 */

package com.caucho.hessian.mux;

import java.io.IOException;
import java.io.InputStream;

/**
 * Input stream to a specific channel.
 */
public class MuxInputStream extends InputStream {
    private MuxServer     server;
    protected InputStream is;
    private int           channel;

    private String        url;

    private int           chunkLength;

    /**
     * Null argument constructor.
     */
    public MuxInputStream()
    {
    }

    /**
     * Initialize the multiplexor with input and output streams.
     */
    protected void init(MuxServer server, int channel)
        throws IOException
    {
        this.server = server;
        this.channel = channel;

        this.url = null;

        chunkLength = 0;
    }

    /**
     * Gets the raw input stream.  Clients will normally not call
     * this.
     */
    protected InputStream getInputStream()
        throws IOException
    {
        if (is == null && server != null)
            is = server.readChannel(channel);

        return is;
    }

    void setInputStream(InputStream is)
    {
        this.is = is;
    }

    /**
     * Gets the channel of the connection.
     */
    public int getChannel()
    {
        return channel;
    }

    /**
     * Returns the request's URL
     */
    public String getURL()
    {
        return url;
    }

    /**
     * Writes a data byte to the output stream.
     */
    public int read()
        throws IOException
    {
        if (chunkLength <= 0) {
            readToData(false);

            if (chunkLength <= 0)
                return -1;
        }

        chunkLength--;
        return is.read();
    }

    /**
     * Complete writing to the stream, closing the channel.
     */
    public void close()
        throws IOException
    {
        skipToEnd();
    }

    /**
     * Skips data until the end of the channel.
     */
    private void skipToEnd()
        throws IOException
    {
        InputStream is = getInputStream();

        if (is == null)
            return;

        if (chunkLength > 0)
            is.skip(chunkLength);

        for (int tag = is.read(); tag >= 0; tag = is.read()) {
            switch (tag) {
                case 'Y':
                    server.freeReadLock();
                    this.is = is = server.readChannel(channel);
                    if (is == null) {
                        this.server = null;
                        return;
                    }
                    break;

                case 'Q':
                    server.freeReadLock();
                    this.is = null;
                    this.server = null;
                    return;

                case -1:
                    server.freeReadLock();
                    this.is = null;
                    this.server = null;
                    return;

                default:
                    int length = (is.read() << 8) + is.read();
                    is.skip(length);
                    break;
            }
        }
    }

    /**
     * Reads tags, until getting data.
     */
    void readToData(boolean returnOnYield)
        throws IOException
    {
        InputStream is = getInputStream();

        if (is == null)
            return;

        for (int tag = is.read(); tag >= 0; tag = is.read()) {
            switch (tag) {
                case 'Y':
                    server.freeReadLock();
                    if (returnOnYield)
                        return;
                    server.readChannel(channel);
                    break;

                case 'Q':
                    server.freeReadLock();
                    this.is = null;
                    this.server = null;
                    return;

                case 'U':
                    this.url = readUTF();
                    break;

                case 'D':
                    chunkLength = (is.read() << 8) + is.read();
                    return;

                default:
                    readTag(tag);
                    break;
            }
        }
    }

    /**
     * Subclasses will extend this to read values.
     */
    protected void readTag(int tag)
        throws IOException
    {
        int length = (is.read() << 8) + is.read();
        is.skip(length);
    }

    /**
     * Reads a UTF-8 string.
     *
     * @return the utf-8 encoded string
     */
    protected String readUTF()
        throws IOException
    {
        int len = (is.read() << 8) + is.read();

        StringBuffer sb = new StringBuffer();

        while (len > 0) {
            int d1 = is.read();

            if (d1 < 0)
                return sb.toString();
            else if (d1 < 0x80) {
                len--;
                sb.append((char) d1);
            }
            else if ((d1 & 0xe0) == 0xc0) {
                len -= 2;
                sb.append(((d1 & 0x1f) << 6) + (is.read() & 0x3f));
            }
            else if ((d1 & 0xf0) == 0xe0) {
                len -= 3;
                sb.append(((d1 & 0x0f) << 12) +
                    ((is.read() & 0x3f) << 6) +
                    (is.read() & 0x3f));
            }
            else
                throw new IOException("utf-8 encoding error");
        }

        return sb.toString();
    }
}
